1993 AMC 8 第 19 题

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19.

下列表达式的值是多少?

(1901+1902+1903++1993)(101+102+103++193) \begin{gathered} \small (1901 + 1902 + 1903 + \cdots + 1993) \\ \small {}- (101 + 102 + 103 + \cdots + 193) \end{gathered}

What is the value of the following expression?

(1901+1902+1903++1993)(101+102+103++193) \begin{gathered} \small (1901 + 1902 + 1903 + \cdots + 1993) \\ \small {}- (101 + 102 + 103 + \cdots + 193) \end{gathered}

167,400167{,}400

172,050172{,}050

181,071181{,}071

199,300199{,}300

362,142362{,}142

答案:A
知识点:配对与分组等差数列
难度评级:960
解答:

第一个和中的每个数都比第二个和中对应的数大 18001800,并且共有 9393 对。

所以差为 93×1800=167,40093 \times 1800 = 167{,}400

所以正确答案是 A

Each number in the first sum is exactly 18001800 more than the matching number in the second sum, and there are 9393 such pairs.

So the difference is 93×1800=167,400.93 \times 1800 = 167{,}400.

Thus, the correct answer is A .

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